heating domestic water with condensate

Tim_10

An owner of a dry cleaners asked my opinion about using condensate to heat domestic water (instead of using boiler water running through the water heater coil). His reasoning was cost savings verses typical gas water heater. At first I though it was plausable, however the more I though about it the less I though it would save money. My question is: what would the additional cost of heating feedwater that is around 100 degrees (temp of condensate after going through the water heater coils) verses feedwater around 170 degrees. He has high pressure steam boiler running @ 110PSI, 650lb/hr. Seems any savings would be lost because of the additional btu input required to heat the feedwater.